docs: def _extract_yaml_docstring(stream):
          '''
          Extract the comments at the top of the YAML file,
          from the stream handler.
          Return the extracted comment as string.
          '''
          comment_lines = []
          lines = stream.read().splitlines()
          for line in lines:
              line_strip = line.strip()
              if not line_strip:
                  continue
              if line_strip.startswith('#'):
                  comment_lines.append(
                      line_strip.replace('#', '', 1).strip()
                  )
              else:
                  break
          return ' '.join(comment_lines)